In general, duct work is commonly used in forced air heating and air-conditioning systems for buildings and the like, with the duct work providing a distribution system to various areas of the building from a furnace and/or air-conditioning system. Coupling a round duct to the furnace or main trunk line is commonly provided via a top take off duct member which is positioned in association with the air handling equipment. The top take off provides the outlet for forced air to exit the trunk line or extended plenum for distribution to the registers. Typically, such a top take off comprises a cylindrical fitting associated with a length of cylindrical tubing which is coupled to an outlet opening in a high pressure plenum of the air handling system. The fitting is installed into and fixed in position with respect to the outlet opening in the wall of a trunk line or plenum. This take off duct can then be coupled into cylindrical duct work which extends to various portions of the building or the like. Depending on the particulars of an installation of an air handling system, it is many times problematic to efficiently couple into the top take off, as the position of the duct work may not correspond to the location of the top take off. Various fittings and interconnections are then necessary to couple the duct work to the air handling system, being a labor intensive and time-consuming process. Attempts to simplify connection of round duct work to a trunk line or plenum have included forming the top take off as an adjustable elbow which allows the orientation and position of the take off to be readily adjusted to simplify positioning and interconnection to the duct system. Such adjustable elbows typically will include three sections, each section being rotatable relative to the others. Each section in the take off is formed so as to be connected at an angular orientation relative to an adjacent section, whereupon relative rotation will vary the orientation of the outlet portion of the take off to simplify coupling into further duct work. Known adjustable take offs may be produced in different ways, but typically utilize a machine which a skilled operator uses for cutting and forming of each of the sections in the take off. Each of the sections may be adjustably coupled to an adjacent section by means of a bead coupling wherein a portion of each section is flared outwardly to engage a similar bead in an adjacent section, thereby locking the pieces together but allowing relative rotation therebetween. Known machines for producing and locking these sections together to form an adjustable take off are problematic, in that many of the stages of production of the sections in the take off are performed manually with a machine for cutting and beading of the take off sections. A skilled operator is therefore necessary to properly form each section and couple the sections together in a manner that they can be adjusted to one another. The difficulty of properly forming each section and connecting the sections together result in a high percentage of scrap as well as take offs which do not function well. More recently, automated take off machines have been produced which are designed to form straight take offs, wherein a cylindrical tube is cut into multiple pieces with the pieces being reassembled and locked together in an adjustable coupling. Although such apparatus is capable of forming a more uniform adjustable coupling between sections of the take off in a repeatable fashion, only straight take offs are able to be manufactured, with each section of the take off having a common diameter.
Other problems associated with these machines include rotation of the cylindrical tube when cutting and forming operations are being performed by the machine. One prior art device has attempted to solve this problem by using an expanding semicircular collar which clamps the work piece against an outer ring. The problem with this device is that the semicircular collar only contacts the work piece at one location. The work piece is still able to move, rotate, or wobble, when undergoing cutting and forming operations. Movement or rotation of the work piece during these operations often results in scrapping of the work piece or in poor interconnection and/or rotational characteristics of the adjustable parts. To improve the efficiency with which the air handling system distributes warm and/or cool air to various areas of the building, it is preferable to increase the velocity of the air as it leaves the plenum of the air handling system and enters the duct work extending to various portions of the building. By tapering the take off duct as it extends from the plenum, the velocity of air introduced into the duct work is significantly increased as desired. For example, a tapered take off may have an initial opening of seven inches for connection to the plenum, while the outlet opening thereof may be reduced to six inches or less. This tapered configuration increases the velocity of the air as it leaves the take off in an effective and inexpensive manner. Of particular advantage is tapering the take off continuously from the inlet to the outlet, or having each gore of the duct tapered. Presently, no apparatus or methods exist for automated manufacture of tapered adjustable ducts, such as for use as a top take off of an air handling system.
Based upon the foregoing, there is a need for an apparatus and methods for automated manufacture of adjustable ducts, and particularly adjustable take offs or elbows. It is therefore a primary objective of this invention to provide an apparatus and methods for manufacturing an adjustable duct member wherein portions of the adjustable duct member are rotatably interlocked with one another to vary the orientation of the outlet side of the duct member. More particularly, there is a need for an apparatus and methods which allow the manufacture of an adjustable take off duct or elbow, wherein a tube of material is cut into gores of predetermined configuration, coupling beads are formed in the gores and the gores are adjustably interconnected to one another to form the finished take off duct in an automated fashion.
Accordingly, the invention provides an improved apparatus for forming an adjustable top take off or elbow duct member for use in an air handling system. The apparatus may comprise a work station adapted to accommodate a work piece. A die associated with the work station is selectively positioned at a predetermined location relative to the work piece positioned in the work station. A cutting and forming assembly associated with the work station cooperates with the die to selectively cut the tapered work piece to form first and second members and to form a coupling bead in the first and second members. The coupling beads cooperate to reconnect the first and second tapered members together at a predetermined angle. The work station may also include a positioning system to position the work piece at a predetermined position for cutting and forming the coupling beads. The work station further includes a clamping assembly to securely hold the work piece a predetermined position during the cutting and forming operations. The clamping system comprises at least two movable clamping members symmetrically positioned about a circumference of, and within the insertion channel. A control system is provided for at least selective control of the clamping, cutting, and forming assemblies. The work station may also include an insertion channel having predetermined dimensions to provide sufficient clearance to accommodate the tapering diameter of a tapered work piece.
The invention is also directed to providing adjustment of the cutting and forming assembly to ensure proper formation of the coupling beads.
The invention also provides a method of manufacturing an adjustable duct member comprising the steps of providing a tube of material for forming the duct member. The tube is positioned in a work station at a first predetermined position relative to a cutting and forming assembly of the work station. The tube is clamped and firmly held into position. The tube is then cut at a first predetermined position to form first and second members, and these members are then positioned in overlapping relationship to one another. A bead is formed in the first and second members at a position to cooperate with one another to allow relative rotation of the first and second members and to interlock these members. The tube may then be repositioned in a work station at a second predetermined position relative to a cutting and forming assembly if a further adjustable section is desired. The tube is clamped and firmly held into position. The tube is cut at a second predetermined position to form first and second members, and these members are positioned in overlapping relationship to one another. A bead is formed in the first and second members at a predetermined position to cooperate with one another to allow relative rotation of the first and second members and interlock these members.
Other objectives and advantages of the invention will become apparent from the following detailed description of a preferred embodiment taken in conjunction with the drawings.